In a method for forming a brittle material at low temperature, using mechanical impact force, such as a conventional aerosol deposition method (Jun Akedo: Oyo Buturi, Vol 68, pp. 44-47, 1999; and Jun Akedo: Science and Industry, Vol 76-2, pp. 1-7, 2002) described in JP-A-2001-3180, impact force is applied to raw material particles by particle collision, the application of ultrasonic waves, or the like, so as to crush the particles, thereby forming newly generated faces, to realize bonds between the particles at low temperature. In this way, a formed article is yielded. By subjecting the raw material particles to pre-treatment of applying mechanical impact force to the particles, with a mill or the like, at this time, so that the raw material particles can be easily crushed by action of slight impact force, there is provided a method in which internal energy is stored, in the form of defects or dislocations, in the raw material particles, and atom diffusion is easily caused by slight stimulation from the outside, so that bonds between the particles can be realized at room temperature.
However, a low-temperature formed article of the brittle material formed in this way conversely contains a great number of defects or dislocations. When this method is applied to electronic material or the like, electrical properties thereof are poorer than those of a material fired at high temperature. Thus, problems remain that limit the scope to which the method can be applied. If the mill treatment to which the raw material particles are subjected before being formed is excessive, surfaces of the raw material particles excessively adsorb impurities, and defects are excessively introduced into the surfaces of the raw material particles. Thus, the density of the formed film or formed article is also decreased. As a result, mechanical properties of the film or the formed article, such as the hardness and Young's module thereof, are also decreased. Thus, problems remain in that practical use thereof is hindered.